Floor hinges are well known. As will be appreciated by those of skill in the art, such hinges typically use a base plate assembly that is bolted or otherwise mounted to the floor so as to remain substantially static. Such hinges also typically include a displaceable frame structure mounted to the door and operatively connected to the base plate assembly. Thus, when the door is moved, there is a relative movement between the frame structure and the base plate assembly. Self returning floor hinges using a spring biased return are also well known. One exemplary spring biased floor hinge is the Model 7811 spring pivot marketed by Bommer Industries, Inc. having a place of business in Landrum, S.C. Such spring biased floor hinges incorporate a spring disposed along a linearly displaceable guide shaft element mounted within the displaceable frame structure. Upon displacement of the door from a pre-established set point, a cam-follower attached to the guide shaft is displaced thereby moving the guide shaft in a linear manner and compressing the spring. The spring compression generates a biasing force along the guide shaft to bring the door back to the pre-established set point. In such prior floor hinges, the linear travel of the guide shaft is maintained by alignment pins extending transverse to the guide shaft and projecting through guide slots in plates above and below the guide shaft. By constraining the pins within the guide slots, the operatively connected guide shaft is thereby limited to substantially linear travel in line with the guide slots as the cam follower is displaced.
Another exemplary spring biased floor hinge is illustrated and described in US patent application 2008/0127452A1 (incorporated by reference). This construction replaces the alignment pins of the Model 7811 with a generally “H” shaped guide plate of hardened steel or the like with a central aperture supporting the guide shaft.
While the prior constructions of self returning floor hinges have performed quite well, the prior products incorporate metal guide plates or pin elements and guide slots to maintain consistent repeatable linear travel. Due to the large number of use cycles that these parts experience, the practice has been to use components of substantial cross-sectional dimension in combination with a relatively heavy cam follower body. Moreover, it has been found that over extended periods of time, the guide slots may tend to experience a degree of wear that varies over the length of the guide slots. This variable wear may give rise to a noticeable clicking sound over the life of the product. Moreover, the use of an “H” shaped guide plate of hardened steel or the like may be difficult to maintain in proper alignment and may impart enhanced wear to a guide shaft during prolonged use.